1. Field of the Invention:
The present invention relates to a recycling automatic document feeder (RADF) usable with a copier or similar equipment for sequentially feeding a stack of documents to a predetermined illuminating position one by one, returning each document undergone illumination to the top of the stack, and repeating such a cycle to illuminate each document a plurality of times.
2. Discussion of Background
A RADF of the type described is useful when a copier is operated to produce plurality of copies with each of a plurality of documents stacked on a table of the copier. Specifically, a RADF automatically feeds a stack of documents from a table thereof one by one, the lowermost document being first, to a glass platen incorporated in the copier by way of a path which forms part of a recycling path. The documents undergone illumination are each returned to the top of the stack remaining on the table by way of another part of the recycling path. Such a procedure is repeated a particular number of times corresponding to the desired number of copies. A conventional RADF has, in addition to the table, a gate pawl, a feeding section, a transporting section, a returning section, sensing means, and control means. The gate pawl is located forwardly of the table with respect to an intended direction of document feed and movable into and out of contact with the table. The feeding section has feeding means for feeding the documents from the table one by one, the lowermost document being first, when the gate pawl is moved away from the table. The transporting section has transporting means for transporting each document fed from the feeding section to a predetermined illuminating position on the glass platen and, after illumination, discharges the document. The returning section has turning means for turning over the document from the transporting section and returns the document having been turned over to the top of the stack remaining on the table. The sensing means is responsive to a condition in which the documents are fed and transported. The control means controls the gate pawl and above-mentioned means in response to the outputs of the sensing means. The gate pawl rests on the top of the stack on the table to divide the stack from documents which are sequentially returned thereto from the returning section.
When a plurality of documents stacked on the table should be repetitively illuminated to produce a plurality of copies with each document, it has been customary that after the last document of the first cycle of documents has been fully discharged onto the top of the stack on the table, the first document of the second cycle of documents is fed to the illuminating position. More specifically, it is only after all the first cycle of documents have been fully discharged that the second cycle of documents start to be fed. The conventional RADF, therefore, consumes a substantial period of time in replacing the first and second cycles of documents. This is especially true with a RADF of the type having a returning section which extends over a long distance, undesirably increasing the illuminating time, i.e., copying time.